Designation:D5521/D5521M−18StandardGuideforDevelopmentofGroundwaterMonitoringWellsinGranularAquifers1ThisstandardisissuedunderthefixeddesignationD5521/D5521M;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thisguidecoversthedevelopmentofscreenedwellsinstalledforthepurposeofobtainingrepresentativeground-waterinformationandwaterqualitysamplesfromgranularaquifers,thoughthemethodsdescribedhereincouldalsobeappliedtowellsusedforotherpurposes.Otherwell-developmentmethodsthatareusedexclusivelyinopen-boreholebedrockwellsarenotdescribedinthisguide.1.2Theapplicationsandlimitationsofthemethodsde-scribedinthisguidearebasedontheassumptionthattheprimaryobjectiveofthemonitoringwellstowhichthemethodsareappliedistoobtainrepresentativewaterqualitysamplesfromaquifers.Screenedmonitoringwellsdevelopedusingthemethodsdescribedinthisguideshouldyieldrela-tivelysediment-freesamplesfromgranularaquifermaterials,rangingfromgravelstosiltysands.Whilemanymonitoringwellsareconsidered“small-diameter”wells(thatis,lessthan10cm[4in.]insidediameter),someofthetechniquesdescribedinthisguidewillbemoreeasilyappliedtolarge-diameterwells(thatis,10cm[4in.]orgreaterinsidediameter).1.3ThevaluesstatedineitherSIunitsorinch-poundunitsaretoberegardedseparatelyasstandard.Thevaluesstatedineachsystemmaynotbeexactequivalents;therefore,eachsystemshallbeusedindependentlyoftheother.Combiningvaluesfromthetwosystemsmayresultinnon-conformancewiththestandard.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.1.5Thisguideoffersanorganizedcollectionofinformationoraseriesofoptionsanddoesnotrecommendaspecifi...
